In order to demonstrate the effects of each risk factor on osteoporotic hip fracture incidence, four main causative models are defined, each has its’ own strengths and weaknesses. These models are listed below:
1) Graphical model 2) Sufficient component cause model 3) Structural equations model 4) Counterfactual model (GIF)
The first two models are qualitative models, but as for evidence based prioritization, quantitative models are needed. While the power and the prevalence of the risk factor are critical, the third model evaluates the power of a risk factor. In the fourth model, the effects of each risk factor on the incidence of the disease are measured.
Murray and Lopez explained four ways to determine the counterfactual status: 1) Reduce the prevalence of a risk factor to the lowest theoretically possible level. (i.e., reducing the prevalence of smoking to zero in a community) 2) Reduce the prevalence of a risk factor to the lowest logically possible level (i.e., the level should be realistic) 3). Reduce the prevalence of a risk factor to the lowest practically possible level (i.e., there are actually some communities in the world, with this level of the risk factor). 4) Reduce the prevalence of the risk factor to the lowest degree that is cost benefit.
It’s obvious that if the goal of an intervention is to reduce the prevalence of a risk factor, considering these four rules one by one, there would be less difference between the current status and the desired level. It seems that using the counterfactual model, the impact of each risk factor can be analyzed. This model identifies the research needs in cases when the available information is not satisfactory, in addition to clarifying the needed data in order to set the points of intervention. With appropriate strategy selection, this kind of analysis can lead to detailed planning for health interventions. Designing and implementing the pilot study leads to the identification of the operational requirements, barriers and related solutions in different field.
This study is the first research that has used the GIF model for evaluating the effects of modifying certain risk factors in the incidence of osteoporotic hip fractures, and no studies have been published about this issue. However, three study was found about GIF model: 1) The Potentially Modifiable Burden of Incident Heart Failure Due to Obesity in USA
, 2) HIV risk factors in Iran; systematic review, meta-analysis and GIF approaches
, 3) causal the composition of risk factors in osteoporosis burden
. In third research, studied risk factors were smoking, low calcium intake, low physical activity, glucocorticoid consumption and low sun exposure. This study concluded that Interventions for improving physical activity, sun exposure are the best approach for reduction of osteoporosis burden in Iran. And also, in our study physical inactivity has the most effect on osteoporotic hip fracture burden. It revealed that interventions to improve in the serum vitamin D level, the consumption of calcium and vitamin D supplements and physical activity are the most effective interventions to reduce the risk of osteoporotic hip fracture.
For evaluating the impact of smoking, the effects of interventions in reducing the prevalence of smoking is trivial especially in women. These limited effects can be attributed to the low prevalence of smoking in the middle-aged men and especially middle-aged and elderly women in comparison with other risk factors. Intervention for the reduction of smoking require to behavioral modification is hard due to poor compliance in this age group.
In order to evaluate the effects of low BMI (less than 20), since there is no clear and distinctive intervention and any intervention that persuades increasing the BMI in this age group, regardless of the effectiveness, can potentially lead to chronic and non-communicable diseases such as diabetes mellitus, cardiovascular diseases and etc. Therefore this risk factor cannot be manipulated easily in the community.
Iran is a country with high prevalence of moderate to severe vitamin D deficiency in both genders. Vitamin D deficiency is highest among people who are elderly. Insufficient vitamin D intake, air pollution
 skin complexion, poor sun exposure, vegetarian food habits and lack of vitamin D fortification program can explain the high prevalence of vitamin D deficiency in Iran
. Pooled analyses in 2012 suggest that high-dose vitamin D supplementation (≥800 IU daily) was somewhat favorable in the prevention of hip fracture and any non-vertebral fracture in persons 65 years of age or older. Furthermore, the data support a 25-hydroxyvitamin D level above 60 nmol/L for prevention of the fractures
Therefore adequate calcium and vitamin D through diet or supplements, taken together, are essential adjuncts to prevent osteoporotic hip fracture. In order to achieve this goal, increase public awareness, educational programs and persuade multidisciplinary cooperation of various governmental and nongovernmental agencies are recommended. General population and the government should be informed that prevention of osteoporotic hip fractures, costs less than their burden to the society. Encouraging people to regular physical activities and allocating public places to exercise as a national plan can be helpful and needs cooperation of various organizations.
The main limitations of this study and the GIF in general is the fact that an adjusted effect measure cannot be used in the GIF formula (while vitamin D deficiency directly affects fracture risk, BMI influences the outcome indirectly and through affecting a chain of intermediate variables); rather, one must stratify by important confounders and use the crude effect measure for each stratum. In addition, it is difficult to determine feasible goals and interventions for the whole population; for instance while strategies to improve vitamin D levels can be easily implemented in a country, it is difficult to determine feasible goals for weight changes. Another limitation of our study is lack of enough information regarding the prevalence and the relative risk of the certain risk factors of osteoporotic hip fracture. In order to get more information about the prevalence of osteoporosis and the burden of the disease, more accurate planning is mandatory.